It’s ok to swallow, it’s only water… Or is it?

You feel the water lever rising in your mouth while you are having a treatment done at the dentist. Your natural instinct raises an alarm in you mind.

I’m going to drown…

I’m choking…

Your eyes open wide and you raise your both hands to make a gesture that you want to get up to empty your mouth. The nurse quickly takes the suction to remove the water but there’s always some left, isn’t there? Your hands are still reaching the spittoon next to the dental chair but the nurse lays a hand on your shoulder and says gently

It’s ok to swallow, it’s only water.

Well is it?

Dental Unit (= the Chair) Waterlines Causing Infections?

The water in dental unit waterlines should match the same standards as safe drinking water. In short this means that the bacterial count (colony forming units, CFU) in the water should not exceed certain safe level (if interested to find out more in depth, please visit here). The standards vary in different countries. The countries I have worked the CFU/ml regulations vary from 100-500. Now here comes the nauseating fact:

In practice the CFU/ml levels can be as high as hundreds of thousands of all sorts of nasty bacteria, including the ones of human origin. Needless to say that it is enough to cause problems.

The problem with the dental units is that many of them are old and do not have the latest technology for waterline cleaning. Renewing the dental units is slow as they are expensive and practices want to use the existing ones as long as possible.

Dental units without waterline cleaning system have a slow flow in the waterlines, the water is warm and the water stands still during off-surgery hours (nights and weekends). Sounds like a very bad combination, eh? The old dental units do not have preventive valves in the waterlines to stop suck back of the patient’s saliva into the lines.

So as a result the waterlines in the dental units are lined with biofilm (a mass or layer of live micro-organisms attached to a surface) that should be removed regularly.

Who Is at Risk?

The healthy patients should not worry much. But to be honest, I do not like to swallow the water myself. It’s gross.

The patients whose immune system is impaired are most at risk. The elderly, the young children, medically compromised people and everyone with immunodeficiency. In worst case scenario the visit at the dentist can be lethal.

Of course us professionals are at risk as well. There are lots of aerosols in the air during the use of the dental unit. A bacterium to raise the biggest concern is the Legionella that causes Legionnaires’ disease. So do take care of the unit waterlines.

Advise for Professional to Improve the Water Quality

Use water source that meets the standards for drinking water.

Run the water from the unit waterlines (handpieces, ultrasonic scalers, air/water syringes):

10 minutes after the weekend
3 minutes in the morning
30 seconds after every patient

Use an efficient waterline treatment product recommended by the unit manufacturer. Use it regularly. Running the water as I advised will get rid of the free flowing bacteria but not the biofilm, it needs an effective disinfectant. The most effective product for getting rid of the biofilm are the ones containing:

hydrogen peroxide
hypochlorite
superoxidized water

Invest in new dental unit (do not go to the cheapest option – you only go from bad to worse) with the latest technology. It’s only humane thing to do.

Conclusion and Cause for Worry

In my experience the dental unit waterlines are not looked after as they should to maintain the good quality of the water.

I have seen that instead of cleaning the waterlines the dental professionals have stopped using the water e.g. when using the slow handpiece (the drill that feels like a street drill). Now I must mention that this happened only in the other country I worked at. I never found out why they actually do this (please enlighten me on comment box below!) but perhaps it was because of the water quality problem? When I used a slow handpiece there, I was naturally worried about overheating of the tooth and tried to get water flowing but it was made impossible.

I have seen a dentist performing implant surgery using a water from air/water syringe (it wasn’t the only thing that was wrong with that treatment – imagine dentist’s tie hanging loose and contaminating everything it touches. Sterile surgical coat was nowhere to be seen). Implant surgery if anything needs an absolute clean environment and wearing your personal clothes and using unit’s water supply simply is not up to the standards.

I know for a fact that many dental nurse neglect running the water as described above. It is appalling thing to do. Honestly.

What does this tell about us professionals? We should be the ones that are looking after the patient’s best interest and health. Doing all the fancy and immaculate maneuvers inside the mouth is not enough to fulfil our purpose.

Are we too busy making money and forgetting the basics?

Advise for the Patients

Seek out a modern dental practice with modern equipment. If you are unsure what modern dental unit looks like, here‘s one example (unfortunately I don’t get paid for advertising this site).

It is ok to ask the nurse or the dentist if the waterlines are regularly disinfected and if the nurse runs the water after each patient.

You are right. “There are lots of aerosols in the air during the use of the dental unit. A bacterium to raise the biggest concern is the Legionella that causes Legionnaires’ disease. So do take care of the unit waterlines.” Aerosols are water droplets we and the patient inhale.